The mechanisms by which people consume content have changed a great deal in recent years. Until recently, books were purchased and read in paper form (typically from a local bookstore); music was listened to via vinyl LP, plastic 8-track or cassette tape, or later digital compact disc (CD); and audio-video was generated via film projector, videocassette, or later digital versatile disc (DVD). Each of these types of content is now frequently obtained in a virtual, electronic format rather than a physical format—books as PDF's or other forms of e-books, music as MP3 files, and audio-visual programs as various forms of digital files. Such content can, in certain circumstances, be fully downloaded from a server system to a client, and then viewed on the client. In other situations, only a portion of the content may be downloaded to the client device—just ahead of the portion that is being presented—in a streaming media format.
Such content delivery systems often fail to provide a satisfying experience for user and for content providers. Content providers may impose digital rights management (DRM) limits on the use of their content to prevent improper use. That may result in a user having to buy a standard-definition copy of a movie and a high-definition copy, in addition to buying a downloaded copy, e.g., if the user wants to watch the movie on his home theatre system (high-definition), portable video players (regular-definition), or smartphone (downloaded copy). Sometimes a user can buy content and be provided with multiple forms of the content, so that the user can enjoy it in different contexts. For example, certain movies are packaged to include a high-definition disk, a regular definition disk, and an electronic file of the movie. Also, some distribution systems, such as individual song downloads are not acceptable to certain artists because they want fans to be presented with an entire contiguous album of music, and with lyric sheets or other items that are important for understanding the artistry of the music.